The Manhattan Project Resources

U.S. Department of Energy

HSS Office of Classification

Office of History and Heritage Resources

Drawing Back the Curtain of Secrecy


1. Fact that development of atomic warheads for guided missiles or artillery is underway - Any elaboration must be cleared by AEC and DOD prior to publication. (51-1)

2. Assembly Systems
a. Gun type
(1) Mere fact that this method may be used to achieve criticality. (51-1)

(2) The description of the propellant material of gun-type weapons. (62-7)

(3) The fact that the 280 mm and 8" gun-type nuclear weapons contain 4 rings. (64-5)
(a) The fact that in the 280 mm gun-type nuclear weapons, the projectile (solid cylinder) is fired into the target rings. (64-5)

(b) The fact that during the firing cycle of the 280 mm, "one portion is detained for a fraction of a second while it is being moved forward." (64-5)

(4) Fact that a specific weapon is gun-type. (67-1)

b. Implosion type
(1) Mere fact that this method may be used to achieve criticality. (51-1)

(2) Moments of inertia of HE implosion type weapons. (62-7)

(3) The fact the MK 7 is an implosion-type nuclear weapon;
(a) The fact that the MK 7 contains 92 detonators;

(b) The fact that two hemispheres "A" and "B" are used in the MK 7 nuclear weapon. (64-5)

(4) Fact that a specific weapon is implosion type except for one classified weapon. (67-1)

c. Mere fact that either method may be used to achieve criticality. (53-1)

d. Design or Functioning of Nuclear Weapons and Components thereof
(1) Implosion weapons
(a) Explosive system; raw materials and detonator cables (unless revealing classified information). (56-3)

(b) In-flight insertion; mere fact that U.S. has a system for nuclear arming of bombs while carrier is in flight (no other details). (56-3)

(2) The definition of a capsule. (67-1)

(3) The fact that the IFI (in-flight insertion of a nuclear material capsule or other nuclear part) safing method was applied to designated, retired weapons. (80-1)

e. Revealing the general fact of existence of nuclear weapons which contain only Pu-239. (67-1) (See also II.M.19.)

f. Use of normal cascade top product in specific weapons. (67-1)

g. Fact of use in specified or unspecified weapons of normal uranium or depleted uranium of any assay. (67-1) (See also II.G.26.)

h. Quantity of Be used outside the nuclear assembly systems. (67-1) (See also II.C.5.)

i. The total quantity of Be used in the nuclear weapons program. (67-1) (See also II.C.6.)

j. The fact of use of B-10 for hardening in unspecified nuclear weapons. (67-1) (See also II.L.3.)

k. The mere fact that delta phase Pu has been or is used in weapons. (67-1) (See also II.M.20.)

l. The fact that (various explosive materials) TNT, RDX, HMX, PETN, RDX COMPOSITION B, RDX COMPOSITION B3, 75/25 CYCLOTOL, BARATOL, TETRYL, PBX 9007, PBX 9010, PBX9011, PBX 9404, PBX 9407, LX-04, and LX-07, are used in specific weapons. (67-1)

m. Fact of use of extrudable explosives in unspecified weapons. (67-1)

n. The fact of use in high explosive assembled (HEA) weapons of spherical shells of fissile materials, sealed pits; air and ring HE lenses; that multipoint detonation systems may be used in weapons, and a definition of pre-initiation-proof weapons (weapon, the yield of which is not sensitive to initiation of the nuclear reaction at a time earlier than the planned time). (72-11)

o. The fact of boosting, the fact that deuterium and tritium are used as boosting fuels in HEA weapons and that they are contained in components known as reservoirs or cartridges which are shipped between the Savannah River Plant and the AEC weapon facilities, the military and the United Kingdom. (72-11) (See also II.A.8. and II.B.9.)
(1) The fact that some high-explosive assembled (HEA) weapons (specified or unspecified) may be boosted or are boosted. (83-2)

(2) Physical state of boosting fuel in HEA weapons. (83-2)

(3) Fact that gaseous deuterium (D) and tritium (T) are used as boosting fuel. (83-2) (See also II.A.8.a. and II.B.9.a.)

(4) The fact that gas boosting is used in specified weapons. (83-3)

(5) Declassification of reservoir information: The safety factor, defined as the ratio of test pressure to maximum working pressure that a reservoir is calculated to experience during its use, for unspecified or specified reservoirs. (93-2)

(6) Boosting information:
(a) The term "hollow boosting." (93-2)

(b) Its definition: "A method wherein the boost gas is in a hollow pit at detonation time." (93-2)

p. The fact of existence of the weapons with tailored outputs, e.g., enhanced x-ray, neutron or gamma-ray output; that we are hardeningour weapons to enhance weapon outputs and that high-Z materials are used in hardening nuclear weapons against high-energy x-rays. (72-11)

q. The mere fact that Be is used in the nuclear assembly system of designated weapons. (72-11) (See also II.C.7.)

r. The fact of existence of a deep-earth penetration fuzing option. (72-11)

s. The mere fact that hollow pits are used as nuclear components. (72-9)

t. The mere fact that weapons may be safed by the insertion of inert materials into the pit. (72-9)

u. The mere fact that some of our nuclear weapons are inherently safe. (72-9)

v. Limited Try - That feature of a coded switch which permits insertion of code possibilities only up to an established number; code tries in excess of an established number may result in a delay or lockout. (73-4)

w. The fact that the MK7 nuclear weapon employed an in-flight-insertion, "levitated pit" design of the type having an airspace between the tamper and core. (79-2)

x. Fact that multidimensional radiation - hydrodynamic codes are used for weapons design. (83-5)

y. Fact of use of slapper detonators in specified weapons. (83-5)

z. Fact of use of multiport valves in specified weapons. (83-5)

aa. Information concerning LLNL's Waxwing device or similar insertable nuclear component (INC) concepts.
(1) The fact that the (HE) used for imploding fissile components of the INC is stored as a paste in the missile body awaiting transfer to a final location. (85-1)

bb. The existence of, or the capability to design, implosion assembled weapons with diameters of 6 inches or more. (88-4)

cc. The concept of storing hydrogen isotopes in solid or liquid compounds in undesignated weapons. (88-4)

dd. Fact that tritium is associated with some unspecified pits. (92-4) (See also II.B.13.)

ee. The fact that some unspecified pits include or contain tritium, no further elaboration. (94-14) (See also II.B.14.)

ff. Declassification of pit bonding information:
(1) Fact that bonding of plutonium or enriched uranium to materials other than themselves is a weapon production process. (93-2)

(2) Fact that such bonding occurs or may occur to specific unclassified tamper, alpha-barrier or fire resistant materials in unspecified pits or weapons. (93-2)

(3) Fact that plutonium and uranium may be bonded to each other in unspecified pits or weapons. (93-2)

(4) Fact that such bonding may be diffusion bonding accomplished in an autoclave or may be accomplished by sputtering. (93-2)

(5) Fact that pit bonding/sputtering is done to ensure a more robust weapon or pit. (93-2)

(6) The use of autoclaves in pit production. (93-2)

(7) The fact that plutonium is processed in autoclaves. (93-2)

(8) The fact that sputtering of fissile materials is done at or for any Department of Energy facility as a production process. (93-2)

(9) The fact of a weapons interest in producing a metallurgical bond between beryllium and plutonium. (93-2)

(10) The fact that beryllium and plutonium are bonded together in unspecified pits or weapons. (93-2)

(11) Routine data concerning concentrations of beryllium in plutonium higher than 100 ppm. (93-2)

gg. That plutonium-239 or weapon-grade plutonium is used:
(1) In unspecified implosion assembled weapons or pits of unspecified staged weapons. (93-2) (See also II.M.29.a.)

(2) As the sole fissile material in unspecified implosion assembled weapons, or in the pit of unspecified staged weapons. (93-2) (See also II.M.29.b.)

hh. Fissile shell information: The fact of use of thin spherical shells of fissile materials in weapons, without elaboration. (93-2)

ii. Special nuclear materials masses: That about 6 kg plutonium is enough hypothetically to make one nuclear explosive device. (93-2) (See also II.M.30)

jj. Hypothetically, a mass of 4 kilograms of plutonium or uranium-233 is sufficient for one nuclear explosive device. (94-1) (See also II.M.30.a.)
NOTE: The average masses of special nuclear materials in the U.S. nuclear weapons or special nuclear materials masses in any specific weapon type remain classified.

3. Initiators:
a. The fact that a modulated external initiator is possible or is used and the fact that initiators of the accelerator type are feasible or are used. (59-7)

b. Fact that an initiator may be or may not be needed in gun-assembled weapons. (59-7)
(1) Fact that initiators may or may not be needed in gun-type weapons. (62-7)

c. The existence and use of modulated initiators of the alpha-n type and that they can use Ac-227, Po-210, Ra-226 and Pu-238. (62-7)
(1) The fact that a polonium-beryllium initiator is used in the 280 mm and 8" gun-type nuclear weapons. (64-5) (See also II.D.4.)

(2) Fact that Po-210 is used in weapon initiators. (67-1) (See also II.D.5.)

d. The fact that accelerator-type initiators are used in gun-assembled weapons. (71-10)

e. The fact that mechanically operated power supplies for accelerator-type initiators are used in gun-assembled weapons. (71-10)

f. The fact that accelerator-type initiators are used in specific weapons. (71-10)

g. The fact that designated weapons are internally initiated. (72-11)

h. Number of neutron generators used in specified weapons. (83-5)

i. External weapon initiator information: The weights, volumes, and physical dimensions of external weapon initiators (neutron generators). (93-2)

**j.The fact that serrations on the inside wall of ceramic neutron tube cylinders are assimbled adjacent to a specified end of the tube. (95-2)

4.External characteristics:
a. Visible size and shape only of specifically listed obsolete weapons of historic interest including replicas and miniatures including nickname, code and model designations: (53-1)
Bikini-Able (w/o external antenna)
Little Boy

b. Nuclear test device shipping and handling containers not revealing nuclear or military characteristics. (53-1)

c. Visible size and shape of externally carried bombs [Note 10] when object is not specifically identified as an atomic weapon and no other information concerning the nature or purpose of the object is revealed to observers. (53-1)
(1) The size, weight and shape of externally carried atomic bombs. (54-2)

d. The size, weight and shape of the 280 MM Atomic Artillery Shell, Mod 0-22 (Army designation: M-354, AEC designation Mark 9). The declassification of the size, weight and shape of artillery-fired atomic shells other than the MK 9 will be considered by AEC-DOD on an individual basis. (54-2)

e. The actual shape, dimensions and weight of the 8-inch artillery shell. (Army designation T317, AEC designation TX 33) (56-2)

f. Actual size, shape, weight, center of gravity, or moments of inertia of fission or boosted fission weapons when identifiable as nuclear weapons provided other classified information is not included. Fat Man, Little Boy, MK 3, MK 4, MK 5 and MK 6 only. (57-4)

g. The actual shape, dimensions and weight of any artillery (or naval rifle) shell whose diameter is equal to or greater than 8 inches. This information will be classified only if the existence of the delivery system is considered classified by the DoD. (57-4)

h. Only such information on the weight of the assembled Davy Crockett weapon as revealed by observation of the physical handling. Note should be taken of the great importance of safeguarding the yield of the Davy Crockett. (60-1)

i. The size, weight, and shape of weapons or missile warheads when in the hands of troops for training, or when final flight test configuration is reached. (62-7)

5. Type of fissionable material used (no reference to quantities; detailed assembly, etc). (53-1)
a. Identification of the type of fissionable materials used in Trinity, Hiroshima, Nagasaki, Bikini-Able, and Bikini-Baker models. (53-1)

b. Use in weapons of normal, depleted or fully enriched uranium and the identification of the fissionable materials used in a specific fission weapon. (59-7) (See also II.G.25.)

c. The fact that reactor grade plutonium can be used to make nuclear weapons. (67-9) (See also II.M.22.)

d. The mere fact that high irradiation level reactor-grade plutonium can be used to make nuclear weapons. (67-10) (See also II.M.23.)

6. Fuzing and Firing Systems [Note 11]
a. The fact that baro, radar, timer, impact, etc., elements may be included in the fuzing systems of atomic weapons. Does not include other details of fuzing system. (53-1)

b. The fact that specific models of nuclear depth bombs of nuclear depth charges use hydrostatic switches to effect a nuclear detonation. (59-6)

c. New developments in non-radiating fuzing for nuclear weapons when evaluation by AEC and DoD indicates no classified information involved. (67-1)

d. The fact of use of ferroelectric or ferromagnetic devices as firing sets in specific weapons. (71-10)

e. Fact of use of compressed-magnetic-field firing sets in specified weapons. (83-5)

*f.The design of the improved Sandia quartz cantilevered beam accelerometer. (95-3)

7. Nomenclature and Description. (56-3)
a. Mere mention of a nuclear weapon by mark, model, service nomenclature number, or code word, whether or not it reveals the device as a nuclear weapon. (56-3)

b. Actual size, weight, center of gravity or moments of inertia of fission weapons when identifiable as nuclear weapons provided information classified by other topics is not included. (56-3)
(1) Obsolete weapons (Fat Man, Little Boy, MK 3 and MK 4 only). Provided external antennae removed. (56-3)

(2) Externally carried weapons. (56-3)

(3) Warheads when completely covered by ballistic case. (56-3)

(4) Shipping and handling containers not revealing nuclear or military information. (56-3)

8. Technology
a. Weapon reliability; Inspection of weapons: Mere fact that such inspections are made. (56-3)

b. Mere existence of the phenomenon of predetonation. (56-3)

c. The term "dial-a-yield" (DAY) and fact of its applicability to undesignated weapons. (89-3)

d. Fact of use of varistors as high voltage limiters. (91-1)

e. Fact that non-spherical parts are used in some weapons, part unidentified, weapon undesignated. (91-1)

f. Fact that fissile and/or fissionable materials are present in some secondaries, material unidentified, location unspecified, use unspecified, and weapons undesignated. (91-1)

g. Fact that multipoint detonation systems are used in undesignated weapons. (91-1)

h. Fact of use of boron carbide in undesignated weapons. (91-1)

i. Fact that the thermal stability of pentaerythritol tetranitrate (PETN) in an undesignated weapon is improved by baking or by adding tripentaery thritol octanitrate, polysaccharide, or other specific additions. (92-2)

j. Primary/secondary information: The identity of a designated device nickname/acronym as a primary or secondary. (93-2) (See also V.D.20.)


1. Research and development
a. Physics of the light elements (includes reactions involving deuterium and tritium). (51-1)

b. General statements concerning the relationship of commonly known nuclear reactions of the light elements to developmental work on thermonuclear weapons. (51-1)

2. Thermonuclear test devices shipping and handling container not revealing nuclear or military characteristics. When object is not specifically identified as an atomic weapon and no other information concerning the nature or purpose of the object is revealed. (53-4)

3. Lithium and its compounds
a. Lithium enriched in the isotope Li6 ; Material up to and including 1 kilogram contained Li6 total. (54-2)

b. Lithium enriched in the isotope Li7 ; Material up to 15 kilograms total contained Li7 . (54-2)

c. Other normal lithium compounds. (54-2)

d. The fact that lithium, deuterium (Li6 D, LiD) are used in unspecified thermonuclear weapons. (62-7) (See also II.Q.7.)

e. The mere fact that normal Lithium Deuteride (Lin D) is used in unspecified TN weapons. (67-1) (See also II.Q.9.)

f. The assay of top product of Li6 production plant or the fact that this top assay is used in weapons. (67-1) (See also II.Q.10.)

g. The fact that Li6 H is used in unspecified weapons for hardening. (67-1) (See also II.Q.11.)

h. The fact the Li7 H or Lin H may be used as mockup materials in the weapons program. (67-1) (See also II.Q.12.)

i. The fact that compounds of Li6 containing tritium are used in the design of weapons as TN fuel. (72-11) (See also II.B.10. and II.Q.13.)

4. The date or estimate of the date when a thermonuclear weapon may be an actuality. (54-2)

5. Visible size and shape only of externally carried thermonuclear weapons when not identifiable as such. (57-1)

6. The size, weight and shape of some thermonuclear weapons (Any information which reveals the existence of thermonuclear weapons with diameter less than 24" or weight less than 2000 lb is classified). (59-7)
a. Size, weight and shape of some thermonuclear weapons (Any information which reveals the existence of thermonuclear weapon with diameter less than 18 inches or weight less than 690 pounds is classified). (60-1)

b. The existence of, or the capability to design, a thermonuclear (TN) weapon assembly system with a diameter of 8 inches or more. (88-4)

7. The fact that certain of our operational missiles have thermonuclear warheads. (62-7)

8. The fact that tests were conducted of designs which could lead to an entirely new class of U.S. weapons which could have relatively low weights and extremely high yields, with the fission contributions decreased to only a few percent of the total yield. (63-1) (See also V.B.5.b.)

9. The fact that the yield-to-weight ratios of the new class of weapons would be more than twice that which can now be achieved in the design of very high yield weapons using previously developed concepts. (63-1)

10. The United States, without further testing, can develop a warhead of 50-60 Mt for B-52 delivery." (63-3)

11. "... some improvement in high yield weapons design could be achieved and that new warheads -- for example a 35 Mt warhead for our Titan II -- based on these improvements could be stockpiled with confidence." (63-3)

12. The salvage value of the Mark 28 Nuclear Weapon recovered off the coast at Palomares, Spain, was $164,000. (67-4)

13. The following information concerning the Palomares, Spain accident. (74-5a)
  • The fact that four TN bombs were involved.
  • The fact that two bombs experienced HE detonation on ground impact.
  • Presence in the bombs of U-235 and Pu-239.

14. The fact that approximately 6 kgs of plutonium were involved in the Greenland accident. (68-4) (See also II.M.24.)
a. Best estimate of the amount of plutonium removed from the site. (68-4) (See also II.M.24.a.)

b. Distribution of Tritium on the surface in the vicinity of the crash (excluding that picked up on aircraft debris) (69-2) (See also II.B.8.)
Enclosed Area1
(square meters)
Tritium Deposition2
(Curies) : (% of total)
1.97 x 103
1.10 x 104
2.49 x 104
3.90 x 104
1 Consecutively larger areas corresponding to the fall-out pattern.
2 Total out to the specified boundary.

15. Information revealing the mere existence of TN devices with total yield equal to or greater than 5 KT. (68-8)

16. The fact that the total number of Spartan and Sprint interceptors planned for the 4-site option at Minuteman sites is 120 Spartans and 264 Sprints. (71-3)

17. The nuclear device to be tested in the Cannikin event is related to the optimum development of a warhead for the Spartan missile of our Safeguard Ballistic Missile Defense Program. The measurements of device performance which will be obtained from the test are essential to our optimum defense deployment of safeguards for protection of our Minuteman missile sites. (71-9) (See also

18. The fact that in thermonuclear (TN) weapons, a fission "primary" is used to trigger a TN reaction in thermonuclear fuel referred to as a "secondary". (72-11)

19. The fact that, in thermonuclear weapons, radiation from a fission explosive can be contained and used to transfer energy to compress and ignite a physically separate component containing thermonuclear fuel. (79-2)
Note: Any elaboration of this statement will be classified.

20. Primary/secondary information: The identity of a designated device nickname/acronym as a primary or secondary. (93-2) (See also V.C.8.j.)

21. Secondary information: The fact that fissile and/or fissionable materials are present in some secondaries, materials unidentified except for uranium (depleted, natural, and enriched including highly enriched uranium), location unspecified, use unspecified, and weapon undesignated. (93-2)

22. Radiation case material information for unspecified weapons only:
a. The fact of use of specific elements with atomic number (Z) greater than 71 as radiation case materials. (93-2)

b. The fact of use of specific unclassified alloys as radiation case materials. (93-2)


1. The fact that DOE weapon laboratories are engaged in a research program to explore the feasibility of a nuclear explosive driven directed energy weapon. (82-2)

2. The fact that research is being conducted on the specific concept of a nuclear pumped X-ray laser. (82-2)
a. The fact that standard laser techniques (e.g., lenses, rods, slabs, and oscillators) were considered in the nuclear-pumped x-ray laser program without discussion of details or experimental results. (94-2)

3. Information concerning Nuclear Directed Energy Weapons (NDEW).
a. The fact that the DOE is interested in or conducting research on NDEW concepts of certain specified generic types of output; i.e., visible light, microwaves, charged particles, kinetic energy. (85-4)

b. The fact that underground tests at the Nevada Test Site have been and are a part of the NDEW research program. (85-4) (See also V.B.3.iii.)

c. The fact that a specified NDEW could engage multiple targets by using multiple beams from a single platform and hence is a high leverage system. (85-4)

d. The fact that an NDEW could have lethal ranges of thousands of kilometers. (85-4)

e. The fact that a kill mechanism for an x-ray laser is ablative shock. (85-4)

4. Information concerning Directed Nuclear Energy Systems.
a. Generalized description of DNES principles, as well as general qualitative or quantitative information on the physics and technology of low-power DNES research, that does not substantially: (86-1)
(1) Assist others in development of DNES weapons; or

(2) Contribute to feasibility assessment of DNES weapon development; or

(3) Reveal programmatic directions.

b. General qualitative descriptions of DNES program goals or objectives that do not reveal classified milestones or achievements or specific design characteristics. Classified milestones and their achievements will be reviewed for release on a case-by-case basis. (86-1)

c. General studies of DNES special nuclear materials and their physical properties. Specific special nuclear materials which are developed for (and the specific conditions of their association with) classified DNES projects and test device designs will remain classified. (86-1)

d. General studies of other DNES materials and their physical properties. No material identities or associations will be declassified where such information may be used to infer classified DNES characteristics. (86-1)

e. General DNES computational techniques or analytical procedures. Computational techniques and procedures which utilize or reveal specific design or operational characteristics will remain classified. (86-1)


1. Existing storage site.
a. Official names(s), nickname(s), and/or location, when association with the Armed Forces Special Weapons Project (AFSWP) or AEC is not revealed. (53-1)

b. AEC storage sites (as pertains to all weapons in custody of AEC at a National Storage Site (NSS) and an Operational Storage Site (OSS)). (56-3)

c. Location
(1) When information does not explicitly reveal installation is a storage site for nuclear weapons. (56-3)

(2) DoD storage sites (as pertains to weapons in DoD custody only). With delivery organizations and operating forces in the U.S. or overseas. (56-3)
(a) Fact that particular aircraft squadron, naval vessel, or special weapons organization has capability of storing or handling nuclear weapons. (56-3)

d. The approximate location of some of the national stockpile sites and operational stockpile sites provided no indication is given as to the total number of storage sites. (59-7)
2. Future storage sites
a. Official name(s), nickname(s), and/or location, when association with AFSWP or AEC is not revealed. Future storage sites become existing storage sites at the time of administrative manning. (53-1)

3. Surveillance program. Mere existence of maintenance or surveillance program. (53-1)

4. "In certain areas Soviet nuclear technology equals and in some areas even exceeds that of the U.S., although our overall capability and means of delivery are believed to be superior to the Soviets." (62-1)

5. "The U.S. has a nuclear weapon in stockpile with a yield of approximately 25 megatons." (62-4)

6. "The world was shocked by the 60 megaton test on October 30th. The U.S. analysis has shown that this device used a lead jacket around the fusion materials, and gave only a few megatons fission. Thus the Russians reduced the fallout, especially that which might have fallen on their own country. If lead were replaced by uranium, the Russian device would give 100 megatons or slightly more." (62-4)

7. The identification of U.S. TX, XW, or Mark numbers with U.S. missile names. (62-7)

8. "In order to achieve it, we maintain a total number of nuclear warheads, tactical as well as strategic, in the tens of thousands." (63-3)

9. The fact that we have deployed thousands of tactical nuclear weapons in Europe. (63-4)
a. The fact that the total kiloton yield of these weapons is well in excess of ten thousand times the total yield of the nuclear weapons used at the end of World War II. (63-4)
10. "This country and the Soviet Union already have produced enough explosive force to equal ten tons of TNT for every man women and child on the face of the earth." This statement was to be used by the President on January 21, 1964 at a Disarmament Conference in Geneva. (64-2)

11. The fact that during the period December 1960 - January 1961 two nuclear artillery shells were in stockpile, the 280 mm and the 8" gun-type nuclear weapons. (64-5)

12. "In presenting this proposal, it could be stated that 'several thousand' nuclear weapons could be involved." This statement is contained in a U.S. Position paper on the Destruction of Nuclear Weapons to Obtain Fissionable Materials for Transfer Under a Cutoff and Transfer Agreement. (65-3)

13. "The number of nuclear warheads in strategic alert forces has increased from 850 on June 30, 1961 to 2700 estimated as of June 30, 1965." (65-5)

14. "The fact that U.S. strategic forces have an inventory of nuclear warheads in excess of 5,000, that the number of nuclear warheads furnished to the Alliance and stored in inventory in Western Europe has exceeded 5,000 nuclear warheads, and that this number will increase by more than 20% during the next six months." (65-7)

15. The minimum spacing for specific nuclear weapons or nuclear components in storage or transit. (67-1)

16. Statements that qualitatively reveal that a nuclear weapon is satisfactory. (67-1)

17. Statements that quantitatively reveal specific component quality or reliability requirements. (67-1)

18. The fact that U.S. nuclear artillery shells are located in Germany. (73-6)

19. The estimated costs for the proposed improved nuclear artillery shells as $452,000 each for the MK-74 (155mm) and $400,000 each for the MK-75 (8 inch). (73-6)

20. The fact that any particular reactor product is being or has been stockpiled for military use. (73-8)

21. Information concerning the weapons stockpile: (81-1)
Fiscal Year

Number of non-nuclear components

1945 1946 1947 1948
1. Gun-type 0 0 (0) (2)
2. Implosion 2 9 (29) (53)
Number of nuclear components
3. Gun-type
0 0 0 0
4. Implosion-type 2 9 13 50
Numbers in parentheses declassified in 1976.
22. Descriptions of historical and future trends in the total number of nuclear weapons in, or megatonage of, the total stockpile which are:
a. Qualitative. (82-1)

b. Expressed as a percentage change over any time period or on an unscaled graph with a scaled time axis for the past, present, or future up to and including the approved period of the current Nuclear Weapons Stockpile Memorandum (usually five fiscal years beyond the current fiscal year). (82-1)
Note: Remains classified if dramatic trend changes result from significant unplanned events such as major technical or production problems, sabotage, natural or man-made disasters, etc.

23. Descriptions of trends for any time period in nuclear weapon production or retirement rates which are qualitative, including relative comparisons of the production rate versus the retirement rate. (82-1)

24. The fact that the total nuclear weapons stockpile contains a few tens of thousands of weapons (no numbers specified). (82-1)

25. The unelaborated fact of the presence of U.S. nuclear weapons in the U.K. (84-1)

26. The megatonage of the United States nuclear stockpile, by year, for year 1945 to 1994. (94-12)

Note: See the data table at Appendix D. for exact data released. Inactive weapons are attributed zero yield. Megatonage value different from the attached table must be approved by Headquarters prior to public release. Specifications by weapon type remains classified.

27. The total quantity of the United States nuclear stockpile, indicated by year, for years 1949 to 1961. The total stockpile quantities for years 1945 to 1948 were already unclassified. (94-12)

Note: Total quantity values that are different from the table at Appendix D. must be approved by Headquarters prior to public release. Specification by weapon type remains classified.

28. The total number of nuclear weapons built by the United States, for weapon types fully retired, by year, for years 1945 to 1989. (94-12)

Note: These are total builds per year only. Specification by weapon type remains classified. Total build numbers that are different from the table at Appendix D. must be approved by Headquarters prior to public release.

29. The total number of nuclear weapons retired by the United States, by year, for years 1945 to 1989. (94-12)

Note: Retirement numbers declassified do not include weapons retired from active status and placed in the inactive stockpile or inactive weapons returned to active status as shown in some classified databases. Retirement numbers that are different from the table at Appendix D. must be approved by Headquarters prior to public release. Specification by weapon type remains classified. The table at Appendix D. includes the number of weapons disassembled by year for years 1980 through 1994. Disassemblies listed in the Appendix reflect only those weapons dismantled for actual disposal. Total disassemblies by year have been unclassified for some time.

30. The total number of nuclear weapons in the United States active and inactive stockpile, by year, for years 1945 to 1961. (94-12)

Note: There were no inactive weapons in the stockpile during this time frame. However, it does allow comment that prior to 1962, all weapons were 'active' and that there were no inactive weapons.


1. The mere fact that the U.S. is interested in pursuing a program to determine the characteristics of an "enhanced radiation" weapon (neutron bomb). (63-5)

2. The fact that we are interested in and are continuing studies on a weapon for minimizing the emerging flux of neutrons and internal induced activity. (67-1)

3. The fact that the W-79 is an enhanced radiation weapon. (78-1)


1. The fact of weapon laboratory interest in MRR devices. (76-3)

2. The fact of successful development of MRR devices. (76-3)

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